Java 在下拉列表中显示从数据库中选择的数据
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Display Selected Data from database in drop down list
提问by newbieinjavaversion2
My goal is to selected data in database and display in drop down list.
我的目标是在数据库中选择数据并显示在下拉列表中。
For example, see the image below show that fbMenuId = M001 (Lasagne).
例如，下图显示 fbMenuId = M001（千层面）。
So at dropdownlist M001 option will be selected. I also need display OTHER MENU like M002,M003,M004,M005,M006 and M007. For example, see the image below
所以在下拉列表中 M001 选项将被选中。我还需要显示其他菜单，如 M002、M003、M004、M005、M006 和 M007。例如，请参见下图
However, my outcome is
然而，我的结果是
Below are my codes
下面是我的代码
<select class="form-control" name="menu" id="menu">
<option value="${order.fbMenuId}" selected>${order.fbMenuName}</option>
<c:forEach var="menu" items="${menu}">
<option value="${menu.fbMenuId}">${menu.fbMenuName}</option>
</c:forEach>
</select>
I am able to display M001 Lasagne. However, there are 2 Lasagne which I do not want. Anyone please help me. Help will be appreciate. Thanks in advance!
我可以展示 M001 千层面。但是，我不想要 2 个千层面。任何人请帮助我。帮助将不胜感激。提前致谢！
Below are codes for servlet and data access object.
下面是 servlet 和数据访问对象的代码。
Servlet
小服务程序
OrderDAO dao = new OrderDAO();
request.setAttribute("order", dao.getOrder(fbOrderId));
request.setAttribute("menu", dao.getMenu(restaurant));
OrderDAO
订单DAO
public OrderBean getOrder(Integer fbOrderId) {
OrderBean ob = new OrderBean();
try {
currentCon = ConnectionManager.getConnection();
Statement statement = currentCon.createStatement();
ResultSet rs = statement.executeQuery("SELECT fborders.fbMenuId, fbMenuName FROM fborders INNER JOIN fbmenu ON fborders.fbMenuId = fbmenu.fbMenuId WHERE fbOrderId='"+ fbOrderId + "'");
while (rs.next()) {
ob.setFbMenuId(rs.getString("fbMenuId"));
ob.setFbMenuName(rs.getString("fbMenuName"));
}
} catch (SQLException e) {
e.printStackTrace();
}
return ob;
}
public ArrayList getMenu(String restaurant) {
ArrayList<OrderBean> am = new ArrayList<OrderBean>();
try {
currentCon = ConnectionManager.getConnection();
Statement statement = currentCon.createStatement();
ResultSet rs = statement
.executeQuery("SELECT fbMenuId, fbMenuName FROM fbmenu WHERE fbRestaurantId='"
+ restaurant + "'");
while (rs.next()) {
OrderBean ob = new OrderBean();
ob.setFbMenuId(rs.getString("fbMenuId"));
ob.setFbMenuName(rs.getString("fbMenuName"));
am.add(ob);
}
} catch (SQLException e) {
e.printStackTrace();
}
return am;
}
采纳答案by newbieinjavaversion2
<select class="form-control" name="menu" id="menu">
<c:forEach var="menu" items="${menu}">
<c:choose>
<c:when test="${menu.fbMenuId == order.fbMenuId}">
<option value="${order.fbMenuId}" selected>${order.fbMenuName}</option>
</c:when>
<c:otherwise>
<option value="${menu.fbMenuId}">${menu.fbMenuName} </option>
</c:otherwise>
</c:choose>
</c:forEach>
</select>
回答by Mahesh Modukuru
As per my understanding, you are showing the selected value twice. one time by appending
根据我的理解，您将两次显示所选值。一次通过附加
<option value="${order.fbMenuId}" selected>${order.fbMenuName}</option>
and another time by iterating the list. Instead of this populate all the values in the dropdown and set the required value as selected. Just write simple condition like the following.
再一次通过迭代列表。而不是填充下拉列表中的所有值并将所需值设置为选定值。只需编写如下简单条件即可。
<select class="form-control" name="menu" id="menu">
<c:forEach var="menu" items="${menu}">
<option value="${menu.fbMenuId}">${menu.fbMenuName}
<c:if test="${menu.fbMenuId == order.fbMenuId}">
selected
</c:if>
</option>
</c:forEach>
</select>
